Engine Hesistation under heavy acceleration

I have a problem that has developed over the past month.

The engine seems to hesitate when I give it heavy throttle. Actually the best way to describe it is like a turbocharger.

If I am cruising at like 25 mph and hit it - It starts to accelerate some as soon as I move the throttle. Then about 1.5-2 seconds later - it really takes off hard all the way to the redline. It should have the harder acceleration from the time I put the throttle down and be
smooth. There is a noticeable jerk when it does take off.

Another way I can describe it is it feels like the 2nd two barrels of the 4 barrel are opening late. It feels like I get max accelleration from the two barrrels and then the second two pop open all the way open and it takes off after about 2 seconds.

If I am pulling up a light border I can't feel any hesisitation. But if I am yanking up a heavy boarder and give it some heavier throttle, I can feel it do the hesitation.

Any ideas? I am going to take the air filter off this weekend while on the lake and see what the carb is doing.

This may be a tough one to track down. It is the PCM 351 engine. 90 Supra Comp TS6M

My boat does something similar. I've been told it is the accelerator pump. I generally don't have to worry about it because it has enough torque to pull wakeboarders up. If I'm pulling a slalom skier, it struggles a little bit to get to 36 mph.